1. Field of the Invention
The present invention generally relates to a radiation shielding door having a fire rating, and more particularly, to a radiation shielding door having a high fire rating and method for making same.
2. Description of the Related Art
Building codes require that doors to be installed in certain building positions need to have a particular fire rating that is measured in time, such as a 20 minute door, a 45 minute door, a one-hour door, a one and one-half hour door, etc. Doors are given a fire rating in accordance with a standard test specification. There are a number of national testing laboratories performing these tests, all of which lead to a “listing” or certification of conformance. Three such listing agencies in the United States are Factory Mutual, Intertek Testing Services, and Underwriters Laboratories.
In conducting such tests, doors are mounted in an opening of a fireproof wall and then exposed on one side to a predetermined time-temperature rise function. The time that a door can withstand the heat before it is penetrated by burning determines its fire rating. A component of the test is a high pressure water stream applied to the door for a set period of time immediately after the door is removed from the test furnace.
An example of a door that provides such a fire rating is disclosed in U.S. Pat. No. 4,104,828, the disclosure of which is incorporated by reference in its entirety. U.S. Pat. No. 4,104,828 discloses a solid fire door having three basic components: a mineral core, wood edges attached around the core (the vertical edges being referred to as stiles and the horizontal edges as rails), and thin facing material covering both sides of the door for its appearance.